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Abstract:

In one aspect, the inventive process comprises a process for pyrolyzing a
hydrocarbon feedstock containing nonvolatiles in a regenerative pyrolysis
reactor system. The inventive process comprises: (a) heating the
nonvolatile-containing hydrocarbon feedstock upstream of a regenerative
pyrolysis reactor system to a temperature sufficient to form a vapor
phase that is essentially free of nonvolatiles and a liquid phase
containing the nonvolatiles; (b) separating said vapor phase from said
liquid phase; (c) feeding the separated vapor phase to the pyrolysis
reactor system; and (d) converting the separated vapor phase in said
pyrolysis reactor system to form a pyrolysis product.

Claims:

1-20. (canceled)

21. An apparatus for pyrolyzing a hydrocarbon feedstock containing
nonvolatiles in a regenerative pyrolysis reactor system, said apparatus
comprising: (a) a heater to heat a nonvolatile-containing hydrocarbon
feedstock to a temperature sufficient to form a vapor phase that is
essentially free of nonvolatiles and a liquid phase containing the
nonvolatiles; (b) a separator to separate the vapor phase from the liquid
phase; and (c) a regenerative pyrolysis reactor system to receive the
separated vapor phase, heat and convert the separated vapor phase in said
pyrolysis reactor system to form a pyrolysis product.

22. The apparatus of claim 21, wherein the pyrolysis reactor comprises
(i) a reaction zone for converting the separated vapor phase to the
pyrolysis product within the reaction zone, and (ii) a quenching zone to
quench the pyrolysis product.

23. The apparatus according to claim 21, wherein the pyrolysis reactor
system comprises a reverse flow regenerative pyrolysis reactor system.

24. The apparatus according to claim 21, wherein separator comprises at
least one of a distillation column, a flash drum, a knock-out drum, a
flash drum having a heating means within the drum, a knock-out drum
having a heating means within the knock-out drum, and combinations
thereof.

25. An apparatus for the manufacture of a hydrocarbon pyrolysis product
from a hydrocarbon feed using a regenerative pyrolysis reactor system,
the apparatus comprising: (a) a heater to heat a nonvolatile-containing
hydrocarbon feedstock to a temperature sufficient to form a vapor phase
that is essentially free of nonvolatiles and a liquid phase containing
the nonvolatiles; (b) a separator to separate the vapor phase from the
liquid phase; and (c) a regenerative pyrolysis reactor system to receive
the separated vapor phase and convert the separated vapor phase in said
pyrolysis reactor system to form a pyrolysis product, the regenerative
pyrolysis reactor system including; (i) a first reactor comprising a
first end and a second end; and (ii) a second reactor comprising primary
end and a secondary end, the first and second reactors are oriented in a
series flow relationship with respect to each other, wherein the first
reactor comprises a first channel for conveying a first reactant through
the first reactor and a second channel for conveying a second reactant
through the reactor.

[0002] This invention pertains to converting hydrocarbons using
regenerative pyrolysis reactors. The invention relates to a process for
cracking hydrocarbons present in hydrocarbon feedstocks containing
nonvolatiles, in a regenerative pyrolysis reactor. The nonvolatiles are
removed from the feedstocks before the hydrocarbons undergo thermal
pyrolysis. More particularly the invention relates to a process and
apparatus for improving the quality of nonvolatile-containing feedstocks
to a regenerative pyrolysis reactor system or a plurality of such
pyrolysis reactor systems.

BACKGROUND OF THE INVENTION

[0003] Conventional steam crackers are known as an effective tool for
cracking high-quality feedstocks that contain a large fraction of
volatile hydrocarbons, such as ethane, gas oil, and naphtha. Similarly,
regenerative pyrolysis reactors are also known and conventionally used
for converting or cracking and to execute cyclic, high temperature
chemistry such as those reactions that may be performed at temperatures
higher than can suitably be performed in conventional steam crackers.
Regenerative reactor cycles typically are either symmetric (same
chemistry or reaction in both directions) or asymmetric (chemistry or
reaction changes with step in cycle). Symmetric cycles are typically used
for relatively mild exothermic chemistry, examples being regenerative
thermal oxidation ("RTO") and autothermal reforming ("ATR"). Asymmetric
cycles are typically used to execute endothermic chemistry, and the
desired endothermic chemistry is paired with a different chemistry that
is exothermic (typically combustion) to provide heat of reaction for the
endothermic reaction. Examples of asymmetric cycles are Wulff cracking,
Pressure Swing Reforming, and other regenerative pyrolysis reactor
processes. Regenerative pyrolysis reactors are generally known in the art
as being capable of converting or cracking hydrocarbons. However, they
have not achieved commercial or widespread use for hydrocarbon
conversion, due at least in part to the fact that they have not been
successfully scaled well to an economical size. This failure is
commercially, due at least in large part to the inability of the
equipment to adequately control and contend with the very high
temperatures and the way that fuel and oxidant are combined during the
regeneration or heating stage of the process. This defect results in
thermal degradation at a commercial scale. The high temperatures are
difficult to position and contain for extended periods of time and lead
to premature equipment failure. A solution was proposed in U.S. patent
application Ser. No. 11/643,541 filed in the USPTO, on Dec. 21, 2006,
entitled "Methane Conversion to Higher Hydrocarbons," related primarily
to methane feedstocks for pyrolysis systems, utilizing an inventive
deferred combustion process.

[0004] As with steam crackers, regenerative pyrolysis reactors also are
well suited for volatized or volatizable feedstocks that are
substantially free of nonvolatile components, such as metals and other
residual or nonvolatizable components, which would otherwise lay down and
build up in the reactor as ash. Pyrolysis reactors typically operate at
higher temperatures than steam crackers. Nonvolatiles may be defined
broadly to mean any resid, metal, mineral, ash-forming, asphaltenic, tar,
coke, or other component, or contaminant within the feedstock that will
not vaporize below a selected boiling point or temperature and which,
during or after pyrolysis, may leave an undesirable residue or ash within
the reactor system. The nonvolatile components of most concern are those
that deposit as ash within the reactor system and cannot be easily
removed by regeneration. Many hydrocarbon coke components may be merely
burned out of the bed at the high temperature typically used in pyrolysis
reactor systems and thus tend to be of less concern than some other
residual components. Some nonvolatile feed components, such as metals
and/or minerals, may leave an ash component behind that even at the high
regeneration temperatures is difficult to remove from a reactor.

[0005] Typically, regenerative reactors include a reactor bed or zone,
typically comprising some type of refractory material, where the reaction
takes place within the reactor system. Conventional regenerative reactors
typically deliver a stream of fuel, oxidant, or a supplemental amount of
one of these reactants, directly to a location somewhere within the flow
path of the reactor bed. The delivered reactants then are caused to
exothermically react therein and heat the reactor media or bed.
Thereafter, the reacted reactants are exhausted and a pyrolysis
feedstock, such as a hydrocarbon feed stream, preferably vaporized, is
introduced into the heated region of the media or bed, and exposed to the
heated media to cause heating and pyrolysis of the reactor feedstock into
a pyrolyzed reactor feed. The pyrolyzed reactor feed is then removed from
the reaction area of the reactor and quenched or cooled, such as in a
quench region of the reactor system, to halt the pyrolysis reaction and
yield a pyrolysis product.

[0006] However, as with steam cracking, economics may favor using lower
cost feedstocks such as, by way of non-limiting examples, crude oil,
heavy distillate cuts, contaminated naphthas and condensates, and
atmospheric resids, as feedstocks for regenerative pyrolysis reactors.
Unfortunately, these economically favored feedstocks typically contain
undesirable amounts of nonvolatile components and have heretofore been
unacceptable as regenerative reactor feedstocks. The nonvolatiles lead to
fouling of the reactor through deposition of materials such as ash,
metals, and/or coke. Regenerative pyrolysis reactors do not have the
flexibility to process such otherwise economically crack favorable
feedstocks because, although coke can typically be burned off, deposits
or buildup of ash and metals within the reactor cannot easily be burned
or removed. The critical concentration of nonvolatiles within a
particular feedstock may vary depending upon variables such as the
intended process, feedstock conditions or type, reactor design, operating
parameters, etc. Generally, nonvolatile concentrations (e.g., ash,
metals, resids, etc.) in excess of 2 ppmw (ppm by weight) of the feed
stream to the reactor will cause significant fouling in a pyrolysis
reactor. Some economically desirable lower cost feeds may contain up to
10 percent by weight of nonvolatiles, while still other feeds may contain
well in excess of 10 weight percent of nonvolatiles. Since nonvolatiles
do not vaporize, but decompose to form ash, metals, tar, and/or coke when
heated above about 600° F. (315° C.) (in an oxidizing
environment), the nonvolatiles present in disadvantaged feedstocks lay
down or build up as a foulant in the reaction section of pyrolysis
reactors, which increases pressure drop through the reactor and leads to
plugging and decreased efficiency. Generally, only low levels of
nonvolatiles (e.g., <2 ppmw and preferably <1 ppmw) or more
specifically low levels of ash (measured by ASTM D482-03 or ISO
6245:2001) can be tolerated in the reactor feeds. Nonvolatiles are
generally determined in accordance with ASTM D6560.

[0007] Various techniques have been employed for treating petroleum
hydrocarbon feeds for the removal of nonvolatiles contained therein to
render cost advantaged feeds suitable for conventional steam cracker
feeds. These processes tend to improve the quality of hydrocarbon feeds
containing nonvolatiles for conventional steam cracking. However, in most
instances the processes suffer from operating condition limitations,
space limitations for retrofits, high capital costs, and high operating
costs, due to the processing steps used, high capital expense of the
required equipment, and/or unsatisfactory reduction limitations in the
amount of nonvolatiles removed from the feeds. For example, it may be
quite costly to equip each of several steam cracking furnaces in a steam
cracking complex with all of the equipment necessary to process the low
cost feedstocks to provide an acceptable, nonvolatile-free feed into the
cracking section of each steam cracker. Similar and even exaggerated
problems exist for a regenerative pyrolysis reactor complex, due to their
feed quality requirements and increased temperature severity.

[0008] The present invention provides a revolutionary process for
improving the quality of nonvolatile-containing hydrocarbon feedstocks to
render such feed suitable for use as a feedstream to a regenerative
pyrolysis reactor system. The invention provides a commercially useful
and cost effective technique for removing the ash-forming nonvolatiles
from the feedstock before the feedstock undergoes pyrolysis in a
regenerative pyrolysis reactor.

SUMMARY OF THE INVENTION

[0009] The present invention relates to pyrolysis of hydrocarbons and in
one embodiment includes a process for reducing ash formation due to
pyrolyzing a hydrocarbon feedstock containing nonvolatiles, in a
regenerative pyrolysis reactor system. In one aspect, the inventive
process comprises a process for pyrolyzing a hydrocarbon feedstock
containing nonvolatiles and reducing ash formation from such process, in
a regenerative pyrolysis reactor system, the process comprising: (a)
heating the nonvolatile-containing hydrocarbon feedstock upstream of a
regenerative pyrolysis reactor system to a temperature sufficient to form
a vapor phase and a liquid phase containing the nonvolatiles; (b)
separating said vapor phase from said liquid phase; (c) transferring or
feeding at least a portion of the separated vapor phase to the
regenerative pyrolysis reactor system; and (d) converting (e.g.,
cracking) at least a portion of the separated vapor phase in the
regenerative pyrolysis reactor system to form a pyrolysis product.
Preferably, the separated vapor phase is substantially free of
nonvolatiles when such vapor phase is fed to the reactor system. Also, it
may be preferable that the regenerative reactor system is a reverse flow
type of regenerative reactor system. In another embodiment, the pyrolysis
reactor system comprises at least two pyrolysis reactor systems and the
separated vapor is cracked in at least two of such pyrolysis reactor
systems. The separated vapor is transferred to and cracked in a reactor
system, preferably in at least two reactor systems substantially
simultaneously by feeding the vapor in parallel flow (e.g., substantially
simultaneously) to the at least two reactor systems.

[0010] In another embodiment, the invention includes the step of feeding a
diluent or stripping agent, such as hydrogen, to the pyrolysis reactor
system in conjunction with the separated vapor phase to the pyrolysis
reactor system for cracking the vapor phase in the presence of the
diluent or stripping agent, within the regenerative pyrolysis reactor
system. Hydrogen may typically be a preferred diluent or stripping agent.
Steam may be used as a diluent or stripping agent for some alternative
processes. However, steam may not be preferred in many processes, in
that, unlike steam cracking, at pyrolysis reactor temperatures, such as
above 1200° C., steam can react with hydrocarbon to form carbon
monoxide and hydrogen.

[0011] In yet another aspect, the invention comprises an inventive process
for the manufacture of a cracked hydrocarbon product, such as olefins,
aromatics, and/or acetylene, from the hydrocarbon feed using a
reverse-flow type regenerative pyrolysis reactor system, wherein the
reactor system includes (i) a first reactor comprising a first end and a
second end, and (ii) a second reactor comprising primary end and a
secondary end, the first and second reactors oriented in a series flow
relationship with respect to each other such that the secondary end of
the second reactor is proximate the second end of the first reactor. In
one aspect, the inventive process comprises the steps of: (a) heating a
nonvolatile-containing hydrocarbon feedstock upstream of the regenerative
pyrolysis reactor system to a temperature sufficient to form a vapor
phase that is essentially free of nonvolatiles and a liquid phase
containing the nonvolatiles; (b) separating the vapor phase from the
liquid phase; (c) supplying a first reactant through a first channel in
the first reactor and supplying at least a second reactant through a
second channel in the first reactor, such that the first and second
reactants are supplied to the first reactor from the first end of the
first reactor; (d) combining the first and second reactants at the second
end of the first reactor and reacting the combined reactants to produce a
heated reaction product; (e) passing the heated reaction product through
the second reactor to transfer at least a portion of the heat from the
reaction product to the second reactor to produce a heated second
reactor; (f) transferring at least a portion of the separated vapor phase
from step (b) as a hydrocarbon feed, and optionally a diluent or
stripping agent, to the pyrolysis reactor system and through the heated
second reactor to the first reactor, to convert at least a portion of the
separated vapor phase feed into a pyrolysis hydrocarbon product; (g)
quenching the pyrolysis product in the first reactor; and (h) recovering
the quenched pyrolysis product from the reactor system.

[0012] In another aspect, the present invention further comprises
condensing the separated vapor phase that is essentially free of
nonvolatiles, storing the condensed hydrocarbons, and subsequently using
the condensed hydrocarbons as feed to a regenerative pyrolysis reactor
system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIGS. 1(a) and 1(b) are a simplified, diagrammatic illustration of
the two steps in a regenerating reverse flow pyrolysis reactor system
according to the present invention.

[0014]FIG. 2 is another diagrammatic illustration of an exemplary
regenerative bed reactor system that defers combustion, controls the
location of the exothermic reaction, and adequately quenches the
recuperation reactor bed.

[0016]FIG. 4 illustrates a cross sectional view of an exemplary gas/vapor
mixer and channels for controlled combustion. FIG. 4A is a cutout view of
a portion of FIG. 4.

[0017]FIG. 5 is a simplified process flow diagram illustrating an
embodiment of the invention.

DETAILED DESCRIPTION

[0018] The terms "convert" and "converting" are defined broadly herein to
include any molecular decomposition, cracking, breaking apart,
conversion, and/or reformation of organic molecules in the hydrocarbon
feed, by means of at least pyrolysis heat, and may optionally include
supplementation by one or more of catalysis, hydrogenation, diluents,
and/or stripping agents.

[0019] As used herein, the expression "essentially free of nonvolatiles"
means that concentration of nonvolatiles in the vapor phase is reduced to
an extremely low level. Those skilled in the art know that it is
difficult to obtain a complete separation of nonvolatiles from a
hydrocarbon feedstock such as crude oil. As a result, the vapor phase may
contain a trace amount of nonvolatiles. Therefore, in the context of the
present invention, while it is the objective that the vapor phase
contains no nonvolatiles, it is recognized that the vapor phase may
contain an acceptable trace amount of nonvolatiles, e.g., typically an
amount of 2 ppmw or less, but still be considered essentially free of
nonvolatiles. The separated vapor phase preferably contains less than 1
ppmw of nonvolatiles. More preferably, the vapor phase contains less than
0.5 ppmw of nonvolatiles. Variables such as the pyrolysis conditions and
reactor design will dictate an appropriate threshold cutoff for
nonvolatile carryover in the vapor phase, for a specific application.

[0020]FIG. 5, illustrates a simplified schematic flow diagram of a
non-limiting embodiment of the invention, including feeding or
transferring a hydrocarbon feedstock that contains nonvolatile components
therein via inlet line (1) to a heat unit/zone (3). Preferred diluent to
hydrocarbon feed molar ratios may range from about 1:1 to about 5:1. Upon
entering the heated, pyrolysis reaction section of the reactor system,
e.g., entering the region of the reactor where the pyrolysis reaction
chemistry or conversion occurs. Stated differently, the amount of diluent
added to the hydrocarbon feedstock or to the separated vapor phase
preferably results in a diluent to separated vapor phase molar ratio of
from about 1:1 to about 5:1. Substantially any hydrocarbon feedstock
containing a mixture of both volatiles and nonvolatiles can
advantageously be utilized in the process. Examples of such feedstock
include one or more of steam cracked gas oil and residues, gas oils,
heating oil, jet fuel, diesel, kerosene, gasoline, coker naphtha, steam
cracked naphtha, catalytically cracked naphtha, hydrocrackate, reformate,
raffinate reformate, Fischer-Tropsch liquids, Fischer-Tropsch gases,
natural gasoline, distillate, naphtha, crude oil, atmospheric pipestill
bottoms, vacuum pipestill streams including bottoms, virgin naphtha, wide
boiling range naphthas, heavy non-virgin hydrocarbon streams from
refineries, vacuum gas oil, heavy gas oil, naphtha contaminated with
crude, atmospheric resid, heavy residuum, C4's/residue admixture,
condensate, contaminated condensate, naphtha residue admixture and
mixtures thereof. The hydrocarbon feedstock may have a nominal end
boiling point of at least 400° F. (200° C.), (e.g., greater
than or equal to 400° F. (200° C.), such as in excess of
1200° F. (650° C.) and even in excess of 1500° F.
(815° C.)) and will commonly have a nominal end boiling point of
at least 500° F. (260° C.). Some preferred hydrocarbon
feedstocks include crude oil, atmospheric resids, contaminated
condensate, and gas oil distillates, tars, fuel oils and cycle oils. The
vaporized hydrocarbon feed may include as a co-feed, substantially any
other hydrocarbon material that undergoes the endothermic reforming, such
as to acetylene, including natural gas mixtures, other petroleum alkanes,
petroleum distillates, kerosene, jet fuel, fuel oil, heating oil, diesel
fuel and gas oil, gasoline, and alcohols. One preferred co-feed may be a
hydrocarbon component that may function as a hydrogen donor diluent, such
as tetralin, and dihydroanthracene, hydropyrene, and hydrotreated steam
cracked tar oils. Preferably, the co-feed will be in a vapor or gaseous
state at the temperature and pressure of introduction into the reactor
system.

[0021] Hydrocarbon streams that have been processed through a refinery,
e.g., naphtha, gas oils, etc., may be suitable reactor feeds. The
inventive process will cleanse the feeds if the same become contaminated
with ash-forming components in their transport to the pyrolysis facility.
However, use of typical light refiner streams may limit the
attractiveness of the process due to the relatively high cost of the
feeds, as compared to other heavier feeds. Heavier, more aromatic feeds
are typically lower cost, per unit weight, but may yield lower acetylene
and ethylene yields and higher carbon or tar yields. Due to the high
aromatic content of the heavier feeds, the feeds have lower hydrogen
content and during pyrolysis, the hydrogen deficit feeds may form tar,
coke, or soot. Conversion in the presence of hydrogen diluent or hydrogen
donor co-feed will provide additional hydrogen available in the reformer
to facilitate better conversion of the separated vapor phase from the
heavier portion of the heavy feeds.

[0022] The amount of nonvolatiles present in the hydrocarbon feedstock
will vary depending upon the feedstock source and quality. For example,
contaminates, full range vacuum gas oils, and petroleum crude oils often
contain relatively high levels of nonvolatile molecules, for example, up
to 20 percent by weight of nonvolatiles. Other feedstocks may contain
even higher concentrations of nonvolatiles. A typical hydrocarbon
feedstock used in the process of the present invention may contain
nonvolatiles in an amount of from about 5 to about 40 weight percent
based upon the weight of the total hydrocarbon feed.

[0023] In heat unit (3), the hydrocarbon feedstock is heated to a
temperature that is sufficient to form a vapor phase and a liquid phase.
The heating of the hydrocarbon feedstock is not limited to any particular
technique. For example, the heating can be conducted by means such as but
not limited to, a heat exchanger, steam injection, submerged heat coil,
or a fired heater. In some embodiments, the heat unit may be a separate
unit, such as illustrated by element (3) in FIG. 5, and in other
embodiments the heat unit may be integrated with or internal to
separation unit (7). The temperature to which the hydrocarbon feedstock
is heated will vary depending upon composition of the hydrocarbon
feedstock and the desired cut-off point for distinguishing between the
vaporized fraction and the liquid fraction. Commonly, the
nonvolatile-containing hydrocarbon feedstock is heated to a temperature
at which at least 50 percent of the liquid phase hydrocarbon feedstock is
converted to a vapor phase, preferably greater than about 90 weight
percent and more preferably greater than 98 weight percent of the
feedstock is vaporized. Exemplary separation vessel temperatures may
range from about 400° F. to about 1200° F. (200° C.
to 650° C.). Preferably, the hydrocarbon feedstock is heated to a
temperature from about 450° F. to about 1000° F.
(230° C. to 540° C.), and more preferably from about
500° F. to about 950° F. (260 to 510° C.). Since the
nonvolatiles contained in the hydrocarbon feedstock are essentially
nonvolatile, they remain within the nonvolatized liquid phase. The
fraction of nonvolatiles in each of the vapor/liquid phases is a function
of both the hydrocarbon partial pressure and the temperature to which the
hydrocarbon feedstock is heated. Desirably, about 50 to about 98 percent
by weight of the heated feedstock will be in the vapor phase. Still more
preferably, at least 90 weight percent of the feedstock will be volatized
into the vapor phase. Vaporizing substantially all of the feedstock may
become more difficult with heavier feedstocks. For identification
purposes, the vaporized or volatized fraction of the separated feed
stream may be referred to herein as the separated vapor phase, even if
such fraction is wholly or fully condensed, partially cooled or
condensed, stored, and/or later revaporized, prior to feeding into the
pyrolysis furnace. Preferably the separated vapor phase is fed to the
pyrolysis furnace in a vapor/gas phase.

[0024] Referring still to FIG. 5, for embodiments having an external or
separate heat and separation units, the heated feedstock is transferred
via line (5) to a separation unit (7), where the vapor phase is separated
from the liquid phase. For integrated or internal heat units, the vapor
phase is separated from the liquid phase in a vapor-liquid separation
unit. Examples of equipment suitable for separating the vapor phase from
the liquid phase include knock-out drum (e.g., substantially any
vapor-liquid separator), a flash drum, two-phase separator, distillation
unit, flash drum having a heating means within the drum, a knock-out drum
having heating means within the known-out drum, and combinations thereof.

[0025] Exemplary heating means may include direct fired heaters, steam,
convection heating, heat exchangers, radiant heating, electric-resistance
heating, or other heat source. In many embodiments, it may be important
to affect the feed stream separation step so that the vapor phase is
essentially free of nonvolatiles (e.g., having less than 1 weight percent
of nonvolatiles carried into the separated vapor phase, based upon the
total weight of the separated vapor phase, determined substantially at or
near the vapor phase exit of the separation vessel.). Otherwise, the
nonvolatiles entrained in the vapor phase will be carried into the
pyrolysis reactor and may cause coking and/or ash problems.

[0026] Heat unit (3) and separation unit (7) are located upstream with
respect to the pyrolysis reactor system. Upstream merely means that the
hydrocarbon feed is first separated into vapor and liquid phases, and
then the vapor phase is transferred to the pyrolysis reactors. There may
also be intermediate steps or processes, such as, for example,
introducing hydrogen into the vapor phase and/or hydrogenation of the
vapor phase before cracking Although the heat unit and separation unit
are depicted in FIG. 5 as separate units, they can be combined into a
single unit ("heat/separation unit"). Examples of suitable
heat/separation units include distillation towers, fractionators, and
visbreakers, as well as knock-out drums and flash drums having a means
within the drum for heating the hydrocarbon feedstock. Examples of
suitable techniques for heating of the hydrocarbon feedstock contained
within the heat/separation unit include injecting hydrogen into the
hydrocarbon feedstock present in the heat/separation unit, heating in a
hydrogenation unit/process, and heaters immersed into the liquid
hydrocarbon feedstock present in the heat/separation unit. Additionally
and preferably, fired heaters may be used to heat the hydrocarbon
feedstock. Heating of the nonvolatile-containing hydrocarbon feedstock
may be carried out such as by fired heater, heat exchanger (either
internal or external, including but not limited to conventional heat
exchangers, submerged internal coils or elements, convection or radiant
heating, induction heating, and/or heat from the reaction system), steam
injection, and/or combinations thereof. Although the heat unit (3) and
separation unit (7) are each shown in FIG. 5 as respective single and
separate units, each of these units can alternatively comprise a
plurality of units, e.g., a separation unit can include more than one
knock-out drums, separators, and/or flash drums. As discussed below, the
heat unit (3) and separation unit (7) may also be combined or integrated
into substantially a common unit.

[0027] For some process embodiments, it may be preferred to maintain a
determined constant ratio of vapor to liquid within the separation unit
(7) or, as the case may be, the heat/separation unit, but such ratio is
difficult to measure and control. However, the temperature of the heated
feedstock before separation can be used as an indirect parameter to
measure, control, and maintain an approximately constant vapor to liquid
ratio in the unit. Ideally, the higher the feedstock temperature, the
higher percentage of hydrocarbons that will be vaporized and become
available as part of the vapor phase for cracking. However, when the
feedstock temperature is too high, nonvolatiles such as coke precursors
could be present in the vapor phase and carried over to the convection
reactor tubes, eventually coking and/or ashing the tubes. The hydrogen
diluent, however, will help suppress coke precursor formation or at least
make it palatable, since the additional free hydrogen produced in the
reactor will facilitate burning off the coke in the reactor. Ashing in
the reactor, however, should still be avoided. A primary objective of the
feed separation step is to remove ashing precursors.

[0028] Conversely, if the temperature of the heated feedstock is too low,
this can result in a low ratio of vapor to liquid with more volatile
hydrocarbons remaining in the liquid phase and not be available for
cracking Adding the hydrogen diluent to the separator and/or the
pyrolysis reactor permits raising the temperature of the separation step
and vessel, as compared to a separation step in the absence of hydrogen.
Thereby, feeding methane or other co-feed and optionally hydrogen diluent
or hydrogen donor diluent, into the separator may even further enable
volatizing a higher percentage of the hydrocarbon feed without formation
of unmanageable ash/coke precursors, as compared to the absence of
hydrogen diluent with the feed.

[0029] The maximum separation temperature of the heated feedstock may also
depend upon the composition of the hydrocarbon feedstock. If the
feedstock contains higher amounts of lighter hydrocarbons, the separation
temperature of the feedstock may be lower while vaporizing an acceptable
percentage of the feed. If the feedstock contains a higher amount of
less-volatile or higher boiling point hydrocarbons, the temperature of
the feedstock may be heated to a higher value for separation, but may
also need the hydrogen diluent. For example, with respect to vacuum gas
oil feeds, the temperature of the heated feedstream may typically be
maintained in the range of from about 400° F. (200° C.) to
about 1200° F. (650° C.).

[0030] In addition to temperature, it is usually also desirable to
maintain a substantially constant hydrocarbon partial pressure to
maintain a substantially constant ratio of vapor to liquid in the
separation vessel. Typically, the hydrocarbon partial pressures for the
heated feedstream are dependent upon the amount of hydrogen or other
stripping agent present in or mixed with the feed. In one aspect of the
inventive process, it may be preferred to combine the co-feed with the
hydrocarbon feed stream either upstream of the separation step or
directly into the separation step. Similarly, hydrogen, or hydrogen donor
diluent may also be added to the hydrocarbon stream upstream of or in the
separation step. The co-feed diluent stream may assist improved
vaporization and separation of the hydrocarbon feed in the heated
separation step. Additional diluent may separately or additionally be
added to the separated vapor stream and/or directly into the pyrolysis
reactor.

[0031] The amount of vapor phase produced in the separation step can vary
widely, depending upon the application and feedstock input rate. For
example, in some applications the vapor phase flow rate may be a vapor
flow rate that has only a partial pyrolysis reactor load, while in other
applications, the vapor flow rate may simultaneously load a plurality
(two or more) of pyrolysis reactors. Still further, in some applications
the vapor phase flow rate may exceed the reactor(s) load capacity for a
particular installation, whereby the excess vapor cut may be condensed
and stored for subsequent use in either steam cracking and/or as
pyrolysis reactor feed, or sent to other applications or uses. For
example, the condensed material can be stored for at least a day, week,
or even longer, such as in tanks or other storage vessels, or sent as
feed to other processes. The determination of total pyrolysis reactor
load capacity is determinable by persons skilled in the processing art.
For example, total load capacity may be calculated from the heat
requirements, flow capacity, reaction requirements, etc. Pyrolysis
capacity is sometimes limited by the heat output capabilities of the
reactor and efficiency with which that heat is utilized and moved through
the reactor system. In some embodiments, the inventive process includes
using multiple pyrolysis reactors, such as at least two pyrolysis reactor
systems, including at least a first pyrolysis reactor system, and the
amount of separated vapor phase is in excess of the reactor capacity of
the first pyrolysis reactor system. Thereby, additional reactors may be
used to handle the total capacity of the transferred vapor phase feed for
pyrolysis. For example, a single heater-separator system may feed two or
more reactor systems, such as a bank of reactor systems.

[0032] Referring still to FIG. 5, the nonvolatile-containing liquid phase
may be withdrawn or removed from separation zone (7) as a bottoms stream,
such as via line (9). This material can be sold as fuel oil or further
processed, e.g., subjected to fluidized catalytic cracking (FCC), coking,
or PDX to produce higher value products, etc. The liquid phase may also
contain resins in addition to nonvolatiles. Resins differ from the
nonvolatiles primarily in having lower molecular weight, less polynuclear
aromatics, more solubility in aliphatic hydrocarbons, and lower in metal
content.

[0033] The separated vapor phase may be withdrawn from separation unit (7)
as an overhead stream via line (11) and passed to one or a plurality (two
or more) of pyrolysis reactors, such as illustrated FIG. 5, depicting two
reactors as pyrolysis reactor systems (17) and (19). The separated,
vaporized hydrocarbons may include various concentrations of associated
gases, such as ethane and other alkanes. The vaporized fraction may also
include impurities, such as H2S and/or nitrogen, and may be sweetened
before feeding to the reactor system. Although two pyrolysis reactors are
illustrated, three or more pyrolysis reactors also may be used in some
applications. Alternatively, the vapor phase essentially free of
nonvolatiles can be removed via line (21), cooled to a liquid in cooling
unit (23), and then transferred via line (25) to storage unit (27).
Although the cooling unit and storage unit are each depicted in FIG. 5 as
separate units, in other applications they may comprise a common (e.g.,
substantially integrated or combined) heat-separator unit. A common
heater-separator unit may include, for example, one or more of a
distillation column, a flash drum having a heating means within the drum,
a knock-out drum having a heating means within the knock-out drum, and
combinations thereof. Some installations may also include a plurality of
common units to serve one or more reactor systems.

[0034] Also, each of the cooling and unit and/or the storage unit may
comprise one or more of such respective unit, e.g., storage unit can
comprise a plurality of tanks The liquid (or a portion thereof) can be
transferred from storage unit (27) via line (29) to line (11) and then
passed or transferred in substantially parallel flow, such as via lines
(13) and (15), to pyrolysis reactors (17) and (19). The cracked reaction
product may then be transferred to product-separation processes, such as
via outlet lines (49) and (51).

[0035] As illustrated in exemplary FIG. 5, the vaporized phase or cut from
the separation in the separating unit (7) (either with or without interim
storage (27)), may be transferred such as via feed line (11) to one or
more pyrolysis reactor systems, such as illustrated by reactor systems
(17) and (19), such as via lines (13) and (15). The separated vapor phase
feed through lines (13) and/or (15) is introduced into the respective
reactor system(s) and heated to a temperature sufficient for conversion
or cracking of the vapor stream to a mix of higher value hydrocarbons,
such as acetylenes.

[0036] According to a preferred process, the separated vapor feed are
exposed to the previously heated hot spot or reaction zone within the
reactor system for a determined appropriate residence time (typically
less than 1.0 second, commonly less than 0.5 seconds, and often less than
0.1 seconds, while a preferred range of 1-100 ms is preferred) and then
quenched to stop the reaction to provide the desired selectivity to a
preferred hydrocarbon product mix or pyrolysis product within the cracked
product stream. Longer reaction times tend to favor the formation of
coke. In many preferred applications, the reaction will be allowed to
proceed for sufficient time to crack the vapor phase hydrocarbons into
smaller components, such as breaking the alkyls to methyl groups (e.g.,
CH4, CH3, and CH2) and hydride radicals. At least a
portion of the introduced or intermediately produced methane or methyl
radicals are converted to acetylene in the reactor system. Aromatic
molecules may similarly be converted to acetylenes or diacetylenes
radicals. A methane co-feed may further help form hydride radicals, which
may help suppress coke and help the reaction proceed to formation of
acetylene. A typical preferred process may also include a relatively high
selectivity (≧0 weight percent) for acetylene within the final
cracked product stream mix. Other exemplary products that may result from
a preferred process may include hydrogen and methane, along with some
other components such as residual coke. Some components of the vaporized
feed stream may be converted within the reactor system, directly to
acetylene. For example, in a high severity regenerative reactor, the high
temperature will start breaking carbons or methyl radicals off of
aliphatic or nonaromatic chains, while the aromatics within the feed may
be reformed directly to acetylenes or diacetylenes. Preferably,
sufficient quenching occurs within the reactor system such that separate
additional quench steps (e.g., heat exchangers, etc.) are not required to
stop the conversion from running beyond the production of a high
selectivity to acetylene. The cracked product mix may include gaseous
hydrocarbons of great variety, e.g., from methane to coke, and may
include saturated, monounsaturated, polyunsaturated, and aromatics. In
some aspects, the pyrolysis product produced is a dilute acetylene stream
(primarily acetylene, with some hydrogen and unreacted methane) that can
be easily hydrogenated to an olefin, such as ethylene, in the vapor phase
or liquid phase. The acetylene hydrogenation reactor could be, for
example, a standard fixed bed process using known hydroprocessing
catalyst.

[0037] In another exemplary process, a vaporized stream from the
separation process may comprise a mix of hydrocarbons, such as aliphatic,
naphthenic, and aromatic compounds. Such vapor stream may be condensed
and stored for later feeding to a regenerative reactor system or fed to
the reactor system without substantially going through an intermediate
condensation step. The regenerative reactor may be heated according to a
regeneration process whereby exothermically reacting components, such as
fuel and oxidant are introduced and reacted in the reactor to heat the
reactor media, with the resulting reaction product removed from the
reactor. Then the vaporized feed may be introduced into or passed through
the heated zone within the reactor.

[0038] Typical conditions may include a residence time from 0.001 to 1.0
seconds and may typically include, for example, a pressure from about 5
to 50 psia (34 to 345 kPa). In some embodiments, the reactor conditions
may be at a vacuum pressure, such as less than 15 psia (103 kPa). Cracked
pyrolysis product may be removed from the reactor system, such as via
lines 49 and/or 51 and transferred to other processes for recovery of the
various component products of the cracked product. The reactor system may
also include additional feed lines (not shown) such as fuel and oxidant
feed, stripping agent feed, exhaust lines, etc.

[0039] The regenerative pyrolysis reactor system according to this
invention is generally a higher temperature hydrocarbon pyrolysis reactor
system than typical steam cracking type hydrocarbon systems that are
conventionally used in commercial steam cracking operations. For example,
commercial naphtha steam cracking operations typically operate at furnace
radiant coil outlet temperatures of less than about 815° C.
(1500° F.). However, the terms "regenerative pyrolysis reactor
systems" as pertaining to the subject invention refers to cyclical
(regenerating) thermal hydrocarbon pyrolysis systems that heat the
hydrocarbon stream to be converted (e.g., the separated vapor phase) to
temperatures of at least 1200° C. (2192° F.), preferably in
excess of 1500° C. (2732° F.), or for some applications,
more preferably in excess of 1700° C. (3092° F.). In some
reactions, it may even be preferable to heat the feeds for very short
time duration, such as less than 0.1 seconds, to a temperature in excess
of 2000° C. (3632° F.). An exemplary preferred process may
pyrolyze the feed stream within the reactor, such as at temperatures of
from about 1500 to about 1900° C., and more preferably from about
1600 to about 1700° C. Exemplary residency times preferably may be
short, such as less than 0.1 seconds and preferably less than about 5
milliseconds. In some aspects, the conversion or cracking of the
separated vapor phase may be performed in the presence of hydrogen,
hydride, other hydrocarbons, and/or other diluents or stripping agents.
The conversion of the vapor fraction into higher value hydrocarbons such
as acetylene typically requires a high reformation temperature, which in
the past has been a significant barrier to commercialization and
efficiency.

[0040] At least part of the invention of the present inventors is the
recognition that the requisite high temperature may be achieved by
creating a high-temperature heat bubble in the middle of a packed bed
system. This heat bubble may be created via a two-step process wherein
heat is (1) added to the reactor bed via delayed, in-situ combustion, and
then (2) removed from the bed via in-situ endothermic reforming. A key
benefit of the invention is the ability to consistently manage and
confine the high temperature bubble (e.g., >1600° C.) in a
reactor region(s) that can tolerate such conditions long term. The
inventive process provides for a substantially continuously operating,
large-scale, cyclic, regenerative reactor system that is useful and
operable on a commercial scale, thereby overcoming the limitations of the
prior art.

[0041] A regenerative reactor system or process may be described generally
as hydrocarbon pyrolysis in a regenerative reactor or more specifically
the conversion of a volatized hydrocarbon stream to acetylene or other
pyrolysis product via thermal pyrolysis of the hydrocarbons in a
regenerative reactor system. One exemplary regenerative pyrolysis reactor
system includes first and second reactors and comprises a reverse flow
type of regenerative pyrolysis reactor system, such as illustrated in
FIGS. 1(a) and 1(b). In one preferred arrangement, the first and second
reactors may be oriented in a series flow relationship with each other,
with respect to a common flow path, and more preferably along a common
center axis. The common axis may be horizontal, vertical, or otherwise. A
regenerative pyrolysis reactor is a cyclical reactor whereby in a first
part of the cycle materials may flow and react for a period of time in
one direction through the reactor, such as to generate and transfer heat
to the reactor media, and then in a second part of the cycle the same
and/or other materials may be fed through the reactor to react in
response to the heat and thereby produce a pyrolysis product. In a
reverse flow type of regenerative pyrolysis reactor, during the second
portion of the cycle the materials flow in an opposite direction as
compared to the direction of material flow in the first portion of the
cycle. The regenerative pyrolysis reactor system contains a reaction zone
that includes the heated or hot area of the reactor where the majority of
the high temperature reaction chemistry takes place, and a quenching zone
that serves to absorb heat from the reacted product and thereby halt the
reaction process or chemistry by cooling the reaction product. At least a
portion of the separated vapor feed that is transferred to or fed into
the reactor system is, generally, (i) cracked in the reaction zone to
form the pyrolysis product, and (ii) that cracked reaction product is
timely quenched in the quenching zone to stop the reaction at the desired
pyrolysis product step to thereby yield the pyrolysis product. If the
reaction is not timely quenched, the reaction may continue breaking the
molecules into either coke, their elemental components, or less desirable
product components.

[0042] The present invention includes a process wherein first and second
in-situ combustion reactants are both separately, but preferably
substantially simultaneously, passed through a quenching reactor bed
(e.g., a first reactor bed), via substantially independent flow paths
(channels), to obtain the quenching (cooling) benefits of the total
combined weight of the first and second reactants. (Although only first
and second reactants are discussed, the regeneration reaction may also
include additional reactants and reactant flow channels.) Both reactants
are also concurrently heated by the hot quench bed, before they reach a
designated location within the reactor system and react with each other
in an exothermic reaction zone (e.g., a combustion zone). This deferred
combustion of the first and second reactants permits positioning
initiation of the exothermic regeneration reaction, in-situ, at the
desired location within the reactor system.

[0043] The reactants are permitted to combine or mix in the reaction zone
to combust therein, in-situ, and create a high temperature zone or heat
bubble (e.g., 1500-1700° C.) inside of the reactor system.
Preferably the combining is enhanced by a reactant mixer that mixes the
reactants to facilitate substantially complete combustion/reaction at the
desired location, with the mixer preferably located between the first and
second reactors. The combustion process takes place over a long enough
duration that the flow of first and second reactants through the first
reactor also serves to displace a substantial portion, (as desired) of
the heat produced by the reaction (e.g., the heat bubble), into and at
least partially through the second reactor, but preferably not all of the
way through the second reactor to avoid waste of heat and overheating the
second reactor. The flue gas may be exhausted through the second reactor,
but preferably most of the heat is retained within the second reactor.
The amount of heat displaced into the second reactor during the
regeneration step is also limited or determined by the desired exposure
time or space velocity that the volatized hydrocarbon feed gas will have
to the reforming, high temperature second reactor media to convert the
volatized hydrocarbon and other hydrocarbons to acetylene.

[0044] After regeneration or heating the second reactor media, in the
next/reverse step or cycle, the volatized hydrocarbon cut from the
previously discussed separation step are fed or flowed through the second
reactor, preferably from the direction opposite the direction of flow
during the heating step. The volatized hydrocarbons contact the hot
second reactor and mixer media, in the heat bubble region, to transfer
the heat to the volatized hydrocarbon for reaction energy. In addition to
not wasting heat, substantially overheating the reformer/second reactor
bed may adversely lead to a prolonged reaction that cracks the
hydrocarbons past the acetylene-generation point, breaking it down into
its elemental components. Thus, the total amount of heat added to the bed
during the regeneration step should not exceed the sum of the heats that
are required (a) to sustain the reforming reaction for the endothermic
conversion of the supplied hydrocarbon to acetylene for a suitable period
of time, as determined by many factors, such as reactor size, dimensions,
vapor flow rates, temperatures used, desired contact time, cycle
duration, etc, and (b) for heat losses from the system both as conduction
losses through reactor walls as well as convective losses with the
exiting products. The total amount of heat stored in the reactor system
though is generally much more heat than would be minimally needed for
conversion on any single cycle. However, it is desirable to avoid having
the temperature bubble so large that the residence time at temperature
becomes too long. As is commonly done for reactor systems, normal
experimentation and refining adjustments and measurements can be made to
the reactor system to obtain the optimum set of reactor conditions.

[0045] In preferred embodiments, the reactor system may be described as
comprising two zones/reactors: (1) a heat recuperating (first)
zone/reactor, and (2) a reforming (second) zone/reactor. As a catalyst is
preferably not required to facilitate reforming the hydrocarbon vapor to
acetylene, so in most preferred embodiments, no catalyst is present in
the reactor beds. However, there may be some applications that benefit
from the presence of a catalyst to achieve a certain range of reforming
performance and such embodiments are within the scope of the invention.

[0046] The basic two-step asymmetric cycle of a regenerative bed reactor
system is depicted in FIGS. 1a and 1b in terms of a reactor system having
two zones/reactors; a first or recuperator/quenching zone (7) and a
second or reaction/reforming zone (1). Both the reaction zone (1) and the
recuperator zone (7) contain regenerative beds. Regenerative beds, as
used herein, comprise materials that are effective in storing and
transferring heat. The term regenerative reactor bed(s) means a
regenerative bed that may also be used for carrying out a chemical
reaction. The regenerative beds may comprise bedding or packing material
such as glass or ceramic beads or spheres, metal beads or spheres,
ceramic (including zirconia) or metal honeycomb materials, ceramic tubes,
extruded monoliths, and the like, provided they are competent to maintain
integrity, functionality, and withstand long term exposure to
temperatures in excess of 1200° C. (2192° F.), preferably
in excess of 1500° C. (2732° F.), more preferably in excess
of 1700° C. (3092° F.), and even more preferably in excess
of 2000° C. (3632° F.) for operating margin.

[0047] As shown in FIG. 1A, at the beginning of the "reaction" step of the
cycle, a secondary end (5) of the reaction zone (1) (a.k.a. herein as the
reformer or second reactor) is at an elevated temperature as compared to
the primary end (3) of the reaction bed (1), and at least a portion
(including the first end (9)) of the recuperator or quench zone (7), is
at a lower temperature than the reaction zone (1) to provide a quenching
effect for the synthesis gas reaction product. A hydrocarbon containing
reactant feed, and preferably also a diluent or stripping agent, such as
hydrogen or steam, is introduced via a conduit(s) (15), into a primary
end (3) of the reforming or reaction zone (1). Thereby, in one preferred
embodiment, the term pyrolysis includes hydropyrolysis.

[0048] The feed stream from inlet(s) (15) absorbs heat from the reformer
bed (1) and endothermically reacts to produce the desired acetylene
product. As this step proceeds, a shift in the temperature profile (2),
as indicated by the arrow, is created based on the heat transfer
properties of the system. When the bed is designed with adequate heat
transfer capability, this profile has a relatively sharp temperature
gradient, which gradient will move across the reaction zone (1) as the
step proceeds. The sharper the temperature gradient profile, the better
the reaction may be controlled.

[0049] The reaction gas exits the reaction zone (1) through a secondary
end (5) at an elevated temperature and passes through the recuperator
reactor (7), entering through a second end (11), and exiting at a first
end (9) as a synthesized gas comprising acetylene, some unconverted
methyls, and hydrogen. The recuperator (7) is initially at a lower
temperature than the reaction zone (1). As the synthesized reaction gas
passes through the recuperator zone (7), the gas is quenched or cooled to
a temperature approaching the temperature of the recuperator zone
substantially at the first end (9), which in some embodiments is
preferably approximately the same temperature as the regeneration feed
introduced via conduit (19) into the recuperator (7) during the second
step of the cycle. As the reaction gas is cooled in the recuperator zone
(7), a temperature gradient (4) is created in the zone's regenerative
bed(s) and moves across the recuperator zone (7) during this step. The
quenching heats the recuperator (7), which must be cooled again in the
second step to later provide another quenching service and to prevent the
size and location of the heat bubble from growing progressively through
the quench reactor (7). After quenching, the reaction gas exits the
recuperator at (9) via conduit (17) and is processed for separation and
recovery of the various components.

[0050] The second step of the cycle, referred to as the regeneration step,
then begins with reintroduction of the first and second regeneration
reactants via conduit(s) (19). The first and second reactants pass
separately through hot recuperator (7) toward the second end (11) of the
recuperator (7), where they are combined for exothermic reaction or
combustion in or near a central region (13) of the reactor system.

[0051] The regeneration step is illustrated in FIG. 1B. Regeneration
entails transferring recovered sensible heat from the recuperator zone
(7) to the reaction zone (1) to thermally regenerate the reaction beds
(1) for the subsequent reaction cycle. Regeneration gas/reactants enters
recuperator zone (7) such as via conduit(s) (19), and flows through the
recuperator zone (7) and into the reaction zone (1). In doing so, the
temperature gradients (6) and (8) may move across the beds as illustrated
by the arrows on the exemplary graphs in FIG. 1(b), similar to but in
opposite directions to the graphs of the temperature gradients developed
during the reaction cycle in FIG. 1(a). Fuel and oxidant reactants may
combust at a region proximate to the interface (13) of the recuperator
zone (7) and the reaction zone (1). The heat recovered from the
recuperator zone together with the heat of combustion is transferred to
the reaction zone, thermally regenerating the regenerative reaction beds
(1) disposed therein.

[0052] In a preferred embodiment of the present invention, a first
reactant, such as a hydrocarbon fuel, is directed down certain channels
(each channel preferably comprising a reactant flow path that includes
multiple conduits) in the first reactor bed (7). In one embodiment, the
channels include one or more honeycomb monolith type structures.
Honeycomb monoliths include extruded porous structures as are generally
known in the reaction industry, such as in catalytic converters, etc. The
term "honeycomb" is used broadly herein to refer to a porous
cross-sectional shape that includes multiple flow paths or conduits
through the extruded monolith and is not intended to limit the structure
or shape to any particular shape. The honeycomb monolith enables low
pressure loss transference while providing contact time and heat
transfer. A mixer is preferably used between the zones (e.g., between or
within a medium between the first and second reactors) to enable or
assist combustion within and/or subsequent to the mixer. Each of the
first channel and the second channel is defined broadly to mean the
respective conductive conduit(s) or flow path(s) by which one of the
reactants and synthesis gas flows through the first reactor bed (7) and
may include a single conduit or more preferably and more likely, multiple
conduits (e.g., tens, hundreds, or even thousands of substantially
parallel conduits or tubes) that receive feed, such as from a gas/vapor
distributor nozzle or dedicated reactant port.

[0053] The conduits each may have generally any cross-sectional shape,
although a generally circular or regular polygon cross-sectional shape
may be preferred. Each channel may preferably provide substantially
parallel, generally common flow through the reactor media. Thus, a first
channel may be merely a single conduit, but more likely will be many
conduits, (depending upon reactor size, flow rate, conduit size, etc.),
for example, such as exemplified in FIG. 2. A channel preferably includes
multiple conduits that each receive and conduct a reactant, such as
delivered by a nozzle in a gas distributor. The conduits may be isolated
from each other in terms of cross flow along the flow path (e.g. not in
fluid communication), or they may be substantially isolated, such that
reactant permeation through a conduit wall into the adjacent conduit is
substantially inconsequential with respect to reactant flow separation.
One preferred reactor embodiment includes multiple segments, whereby each
segment includes a first channel and a second channel, such that after
exiting the reactor, the respective first reactant is mixed with the
respective second reactant in a related mixer segment. Multiple segments
are included to provide good heat distribution across the full
cross-sectional area of the reactor system.

[0054] Referring to FIG. 4, mixer segment (45), for example, may mix the
reactant flows from multiple honeycomb monoliths arranged within a
particular segment. Each monolith preferably comprises a plurality (more
than one) of conduits. The collective group of conduits that transmit the
first reactant may be considered the first channel and a particular
reactor segment may include multiple collective groups of monoliths
and/or conduits conducting the first reactant, whereby the segment
comprising a channel for the first reactant. Likewise, the second
reactant may also flow through one or more monoliths within a segment,
collectively constituting a second channel. Thus, the term "channel" is
used broadly to include the conduit(s) or collective group of conduits
that conveys at least a first or second reactant. A reactor segment may
include only a first and second channel, or multiple channels for
multiple flow paths for each of the first and second reactants. A mixer
segment (45) may then collect the reactant gas from both or multiple
channels. Preferably, a mixer segment (45) will mix the effluent from one
first channel and one second channel.

[0055] It is recognized that in some preferred embodiments, some or even
several of the conduits within a channel will likely convey a mixture of
first and second reactants, due at least in part to some mixing at the
first end (17) of the first reactor. However, the numbers of conduits
conveying combustible mixtures of first and second reactants is
sufficiently low such that the majority of the stoichiometrically
reactable reactants will not react until after exiting the second end of
the first reactor. The axial location of initiation of combustion or
exothermic reaction within those conduits conveying a mixture of
reactants is controlled by a combination of temperature, time, and fluid
dynamics. Fuel and oxygen usually require a temperature-dependent and
mixture-dependent autoignition time to combust. Still though, some
reaction will likely occur within an axial portion of the conduits
conveying a mixture of reactants. However, this reaction is acceptable
because the number of conduits having such reaction is sufficiently small
that there is only an acceptable or inconsequential level of effect upon
the overall heat balance within the reactor. The design details of a
particular reactor system should be designed so as to avoid mixing of
reactants within the conduits as much as reasonably possible.

[0056] The process according to the present invention requires no large
pressure swings to cycle the reactants and products through the reactor
system. In some preferred embodiments, the reforming or pyrolysis of
volatized hydrocarbon step occurs at relatively low pressure, such as
less than about 50 psia, while the regeneration step may also be
performed at similar pressures, e.g., less than about 50 psia, or at
slightly higher, but still relatively low pressures, such as less than
about 250 psia. In some preferred embodiments, the volatized hydrocarbon
pyrolysis step is performed at a pressure of from about 5 psia to about
45 psia, preferably from about 15 psia to about 35 psia. Ranges from
about 7 psia to about 35 psia and from about 15 psia to about 45 psia are
also contemplated. The most economical range may be determined without
more than routine experimentation by one of ordinary skill in the art in
possession of the present disclosure. Pressures higher or lower than that
disclosed above may be used, although they may be less efficient. By way
of example, if combustion air is obtained from extraction from a gas
turbine, it may be preferable for regeneration to be carried out at a
pressure of, for example, from about 100 psia to about 250 psia. However,
by way of further example, if the process is more economical with air
obtained via fans or blowers, the regeneration may be carried out at
lower pressures such as 15-45 psia. In one embodiment of the present
invention, the pressure of the pyrolysis and regeneration steps are
essentially the same, the difference between the pressures of the two
steps being less than about 10 psia.

[0057] It is understood that some method of flow control (e.g. valves,
rotating reactor beds, check valves, louvers, flow restrictors, timing
systems, etc.) is used to control gas flow, actuation, timing, and to
alternate physical beds between the two flow systems. In the regeneration
step, air and fuel must be moved through the reactor system and combined
for combustion. Air can be moved such as via compressor, blower, or fan,
depending on the operating conditions and position desired for the
reactor. If higher pressure air is used, it may be desirable to expand
the flue gas through an expansion turbine to recover mechanical energy.
In addition, some fraction of exhaust gas may be recycled and mixed with
the incoming air. An exhaust gas recycle (EGR) stream may be supplied
with at least one of the supplied first reactant and second reactant in
the first reactor. This EGR may be used to reduce the oxygen content of
the regeneration feed, which can reduce the maximum adiabatic flame
temperature of the regeneration feed. In the absence of EGR, CH4/air
mixtures have a maximum adiabatic flame temperature of about 1980°
C.; H2/air mixtures are about 2175° C. Thus, even if average
temperature is controlled by limiting the flow rate of fuel, any poor
diluting could result in local hot spots that approach the maximum flame
temperature. Use of EGR can reduce the maximum hot spot temperature by
effectively increasing the amount of diluent such as N2 (and
combustion products) that accompany the oxygen molecules.

[0058] For example, when 50 percent excess air is used for combustion, the
maximum adiabatic flame temperature for H2-fuel/air combustion
decreases from about 3947° F. (2175° C.) to about
2984° F. (1640° C.). Reducing the oxygen content of the
supplied air to about 13 percent would make about 2984° F.
(1640° C.) the maximum adiabatic flame temperature, regardless of
local mixing effects. The reforming or pyrolysis step and flow scheme is
illustrated in FIG. 1(a). The vapor phase of the separation of the
hydrocarbon feed stream is transferred to the reactor system inlet,
preferably mixed with or supplied with hydrogen or a source for hydrogen
as a diluent or stripping agent, either within the second reactor or
prior to entry into the second reactor, and is pyrolyzed in the high
temperature heat bubble created by the regeneration step.

[0059] After leaving the second reactor and the optional mixer, the
pyrolyzed product stream must be cooled or quenched to halt the
conversion process at the acetylene or other appropriate stage. The
timing for this step is important because the reaction is not timely and
properly quenched, some desired products, such as acetylene, will be
passed by the reaction and the pyrolysis product will not have the
desired selectivity to the valuable or desired products. Some pyrolysis
products, however, are still rarely a desired final material for process
export. Rather, a preferred use for the produced pyrolysis products, such
as acetylene, is as an intermediate product in a flow process within a
chemical plant, in route to other preferred products, such as vinyl
esters, ethylene, acetaldehyde, propanal, and/or propanol, acrylic acid,
and so on. Typical desired pyrolysis products may be an olefin and/or an
alkyne. Some commonly desired olefins may include ethylene, propylene,
and/or butylene. Some commonly desired alkynes may include acetylene.

[0060] After quenching, the synthesized gas stream may be provided to a
separation process that separates the acetylene, methane, hydrogen, and
other gases. Recovered methane and hydrogen may be recycled for
processing again in the reactor system. Separate process sequences may
convert the acetylene to other final products. Each of these products may
be further processed to provide yet additional useful products, e.g.,
acetaldehyde is typically an intermediate in the manufacture of ethanol,
acetic acid, butanals, and/or butanols. Ethylene is a basic building
block of a plethora of plastics, and may typically be the preferred use
for the created acetylene, from the perspective of volume and value.
Ethylene is conveniently manufactured from acetylene by hydrogenation. In
some embodiments of the invention, it may also be a coproduct of the
inventive volatized hydrocarbon conversion process. Another product of
high interest is ethanol, which may be conveniently manufactured by first
hydrating the acetylene to acetaldehyde and then hydrogenating
acetaldehyde to ethanol. Ethanol is of interest because it is easily
transported from a remote location and is easily dehydrated to ethylene.
Ethanol may also be suitable for use as a motor fuel, if the
manufacturing can be sufficiently low in cost.

[0061] Conversion of a volatized hydrocarbon stream to acetylene leaves a
surplus of hydrogen. An idealized reaction is to crack the aliphatic
chains into various methyl groups and continue the pyrolysis reaction via
further conversion of the methyls to acetylene. An exemplary reaction for
conversion of methane is:

2CH4→C2H2+3 H2 consuming about+45 kcal/mole
of converted CH4

[0062] As suggested by the above reaction, hydrogen is a valuable
by-product of the present process. To a lesser extent, ethylene and
propylene are also valuable products, produced as a result of incomplete
reduction of volatized hydrocarbon to higher hydrocarbon. Unreacted
volatized hydrocarbon is also a valuable product for recovery.
Accordingly, separation and recovery of hydrogen, separation and recovery
of olefins such as ethylene and propylene, and separation and recovery of
unconverted volatized hydrocarbon vapor feed are each individually and
collectively preferred steps in the process according to the invention.
Unconverted volatized hydrocarbon is preferably returned to the
hydropyrolysis reactor so that it may be converted on a second pass. An
amount of hydrogen should also be returned to the hydropyrolysis reactor
that is sufficient to control the selectivity of the product
distribution.

[0063] Since hydrogen is created (not consumed) in the reforming pyrolysis
reaction, it will be necessary to purge hydrogen from the process. For
example, conversion of methane to acetylene, with subsequent
hydrogenation to ethylene, will generate about one H2 for every
CH4 converted. Hydrogen has a heat of combustion of about 57
Kcal/mole H2, so the hydrogen purged from the process has a heating
value that is in the range of what is needed as regeneration fuel. Of
course, if there is an alternate, high-value use for the leftover
hydrogen, then natural gas could be used for all or part of the
regeneration fuel. But the leftover hydrogen is likely to be available at
low pressure and may possibly contain methane or other diluents. Thus,
use of hydrogen as regeneration fuel may also be an ideal disposition in
a remote location. However, heavier feeds may not make as much excess
hydrogen, and in some instances may not make any appreciable volumes of
excess hydrogen. The amount of excess hydrogen generated will depend
strongly on the overall hydrogen to carbon ratio of the feedstock and
upon the desired ultimate product. For example, an ethylene product will
result in less excess hydrogen than an ethyne (acetylene) product.

[0064]FIG. 2 illustrates another exemplary reactor system that may be
suitable in some applications for controlling and deferring the
combustion of fuel and oxidant to achieve efficient regeneration heat.
FIG. 2 depicts a single reactor system, operating in the regeneration
cycle. The inventive reactor system preferably comprises two reactors
zones or two reactor zones. The recuperator (27) is the zone primarily
where quenching takes place and provides substantially isolated flow
paths or channels for transferring both of the quenching reaction gases
through the reactor media, without incurring combustion until the gases
arrive proximate or within the reactor core (13) in FIG. 1. The reformer
(2) is the reactor where regeneration heating and volatized hydrocarbon
reformation primarily occurs, and may be considered as the second reactor
for purposes herein. Although the first and second reactors in the
reactor system are identified as separately distinguishable reactors, it
is understood and within the scope of the present invention that the
first and second reactors may be manufactured, provided, or otherwise
combined into a common single reactor bed, whereby the reactor system
might be described as comprising merely a single reactor that integrates
both cycles within the reactor. The terms "first reactor" and "second
reactor" merely refer to the respective zones within the reactor system
whereby each of the regeneration, reformation, quenching, etc., steps
take place and do not require that separate components be utilized for
the two reactors. However, most preferred embodiments will comprise a
reactor system whereby the recuperator reactor includes conduits and
channels as described herein, and the reformer reactor may similarly
possess conduits. Other preferred embodiments may include a reformer
reactor bed that is arranged different from and may even include
different materials from, the recuperator reactor bed. The bedding
arrangement of the reformer or second reactor may be provided as desired
or as prescribed by the application and no particular design is required
herein of the reformer reactor, as to the performance of the inventive
reactor system. Routine experimentation and knowledge of the volatized
hydrocarbon pyrolysis art may be used to determine an effective
reformer/second reactor design.

[0065] As discussed previously, the first reactor or recuperator (27)
includes various gas conduits (28) for separately channeling two or more
gases following entry into a first end (29) of the recuperator (27) and
through the regenerative bed(s) disposed therein. A first gas (30) enters
a first end of a plurality of flow conduits (28). In addition to
providing a flow channel, the conduits (28) also comprise effective flow
barriers (e.g., which effectively function such as conduit walls) to
prevent cross flow or mixing between the first and second reactants and
maintain a majority of the reactants effectively separated from each
other until mixing is permitted. In a preferred embodiment of the present
invention, the recuperator is comprised of one or more extruded honeycomb
monoliths. A small reactor may include a single monolith, while a larger
reactor can include a number of monoliths, while still larger reactor may
be substantially filled with an arrangement of many honeycomb monoliths.

[0066] Honeycomb monoliths preferred in the present invention (which are
adjacent a first end (9) of the first reactor (7)) can be characterized
as having open frontal area (or geometric void volume) between about 40
percent and 80 percent, and having conduit density between about 50 and
2000 pores per square inch, more preferably between about 100 and 1000
pores per square inch. (For example, in one embodiment, the conduits may
have a diameter of only a few millimeters, and preferably on the order of
about one millimeter.) Reactor media components, such as the monoliths or
alternative bed media, preferably provide for at least one of the first
and second channels and preferably both channels to include a packing
with an average wetted surface area per unit volume that ranges from
about 50 ft-1 to about 3000 ft-1, more preferably from about
100 ft-1 to 2500 ft-1, and still more preferably from about 200
ft-1 to 2000 ft-1, based upon the volume of the first reactor
that is used to convey a reactant. These wetted area values apply to the
channels for both of the first and second reactants. These relatively
high surface area per unit volume values are likely preferred for many
embodiments to aid achieving a relatively quick change in the temperature
through the reactor, such as generally illustrated by the relatively
steep slopes in the exemplary temperature gradient profile graphs, such
as in FIGS. 1(a), 1(b), and 5. The quick temperature change is preferred
to permit relatively quick and consistent quenching of the reaction to
prevent the reaction from continuing and creating coke.

[0067] Preferred reactor media components also provide for at least one of
the first and second channels in the first reactor and more preferably
for both channels, to include a packing that includes a high volumetric
heat transfer coefficient (e.g., greater than or equal to 0.02
cal/cm3s° C., preferably greater than about 0.05
cal/cm3s° C., and most preferably greater than 0.10
cal/cm3s° C.), have low resistance to flow (low pressure drop),
have operating temperature range consistent with the highest temperatures
encountered during regeneration, have high resistance to thermal shock,
and have high bulk heat capacity (e.g., at least about 0.10
cal/cm3° C., and preferably greater than about 0.20
cal/cm3° C.). As with the high surface area values, these
relatively high volumetric heat transfer coefficient value and other
properties are also likely preferred for many embodiments to aid in
achieving a relatively quick change in the temperature through the
reactor, such as generally illustrated by the relatively steep slopes in
the exemplary temperature gradient profile graphs, such as in FIGS. 1(a),
1(b), and 5. The quick temperature change is preferred to permit
relatively quick and consistent quenching of the reaction to prevent the
reaction from continuing too long and creating coke or carbon buildup.
The cited values are averages based upon the volume of reactor used for
conveyance of a reactant.

[0068] Alternative embodiments may use reactor media other than the
described and preferred honeycomb monoliths, such as whereby the channel
conduits/flow paths may include a more tortuous pathways (e.g.
convoluted, complex, winding and/or twisted but not linear or tubular),
than the previously described monoliths, including but not limited to
labyrinthine, variegated flow paths, conduits, tubes, slots, and/or a
pore structure having channels through a portion(s) of the reactor and
may include barrier portion, such as along an outer surface of a segment
or within sub-segments, having substantially no effective permeability to
gases, and/or other means suitable for preventing cross flow between the
reactant gases and maintaining the first and second reactant gases
substantially separated from each other while axially transiting the
recuperator (27). For such embodiments, the complex flow path may create
a lengthened effective flow path, increased surface area, and improved
heat transfer. Such design may be preferred for reactor embodiments
having a relatively short axial length through the reactor. Axially
longer reactor lengths may experience increased pressure drops through
the reactor. However for such embodiments, the porous and/or permeable
media may include, for example, at least one of a packed bed, an
arrangement of tiles, a permeable solid media, a substantially
honeycomb-type structure, a fibrous arrangement, and a mesh-type lattice
structure. It may be preferred that the media matrix provides high
surface area to facilitate good heat exchange with the reactant and
produced gases.

[0069] It may be preferred to utilize some type of equipment or method to
direct a flow stream of one of the reactants into a selected portion of
the conduits. In the exemplary embodiment of FIG. 2, a gas distributor
(31) directs a second gas stream (32) to second gas stream channels that
are substantially isolated from or not in fluid communication with the
first gas channels, here illustrated as channels (33). The result is that
at least a portion of gas stream (33) is kept separate from gas stream
(30) during axial transit of the recuperator (27). In a preferred
embodiment, the regenerative bed(s) of the recuperator zone comprise
channels having a gas or fluid barrier that isolates the first reactant
channels from the second reactant channels. Thereby, both of the at least
two reactant gases that transit the channel means may fully transit the
regenerative bed(s), to quench the regenerative bed, absorb heat into the
reactant gases, before combining to react with each other in the
combustion zone.

[0070] By keeping the reactants (30) and (32) substantially separated, the
present invention defers or controls the location of the combustion or
other heat release that occurs due to exothermic reaction. "Substantially
separated" means that at least 50 percent, preferably at least 75
percent, and more preferably at least 90 percent of the reactant having
the smallest or limiting stoichiometrically reactable amount of reactant,
as between the first and second reactant streams, has not become consumed
by reaction by the point at which these gases have completed their axial
transit of the recuperator (27). In this manner, the majority of the
first reactant (30) is kept isolated from the majority of the second
reactant (32), and the majority of the heat release from the reaction of
combining reactants (30) and (32) will not take place until the reactants
begin exiting the recuperator (27). Preferably the reactants are gases,
but some reactants may comprise a liquid, mixture, or vapor phase.

[0071] The percent reaction for these regeneration streams is meant the
percent of reaction that is possible based on the stoichiometry of the
overall feed. For example, if gas (30) comprised 100 volumes of air (80
volumes N2 and 20 Volumes O2), and gas (32) comprised 10
volumes of Hydrogen, then the maximum stoichiometric reaction would be
the combustion of 10 volumes of hydrogen (H2) with 5 volumes of
Oxygen (O2) to make 10 volumes of H2O. In this case, if 10
volumes of hydrogen were actually combusted in the recuperator zone (27),
this would represent 100 percent reaction of the regeneration stream.
This is despite the presence of residual un-reacted oxygen, because that
un-reacted oxygen was present in amounts above the stoichiometric
requirement. Thus, the hydrogen is the stoichiometrically limiting
component. Using this definition, it is preferred that less than 50
percent reaction, more preferred that less than 25 percent reaction, and
most preferred that less than 10 percent reaction of the regeneration
streams occur during the axial transit of the recuperator (27).

[0072] In a preferred embodiment, the channels (28) and (33) comprise
materials that provide adequate heat transfer capacity to create the
temperature profiles (4) and (8) illustrated in FIG. 1 at the space
velocity conditions of operation. Adequate heat transfer rate is
characterized by a heat transfer parameter ΔTHT, below about
500° C., more preferably below about 100° C. and most
preferably below about 50° C. The parameter ΔTHT, as
used herein, is the ratio of the bed-average volumetric heat transfer
rate that is needed for recuperation, to the volumetric heat transfer
coefficient of the bed, hv. The volumetric heat transfer rate (e.g.
cal/cm3 sec) that is sufficient for recuperation is calculated as
the product of the gas flow rate (e.g. gm/sec) with the gas heat capacity
(e.g. ca./gm ° C.) and desired end-to-end temperature change
(excluding any reaction, e.g. ° C.), and then this quantity
divided by the volume (e.g. cm3) of the recuperator zone (27)
traversed by the gas. The ΔTHT in channel (28) is computed
using gas (30), channel (33) with gas (32), and total recuperator zone
(27) with total gas. The volumetric heat transfer coefficient of the bed,
hv, is typically calculated as the product of a area-based coefficient
(e.g. cal/cm2s° C.) and a specific surface area for heat
transfer (av, e.g. cm2/cm3), often referred to as the wetted
area of the packing

[0073] In a preferred embodiment, channels (28) and (33) comprise ceramic
(including but not limited to zirconia), alumina, or other refractory
material capable of withstanding temperatures exceeding 1200° C.,
more preferably 1500° C., and still more preferably 1700°
C. Materials having a working temperature of up to and in excess of
2000° C. might be preferred where there is concern with reaching
the bed reaction adiabatic maximum temperature for sustained periods of
time, to prevent reactor bed damage, provided the project economics and
conditions otherwise permit use of such materials. In a preferred
embodiment, channels (28) and (33) have wetted area between 50 ft-1
and 3000 ft-1, more preferably between 100 ft-1 and 2500
ft-1, and most preferably between 200 ft-1 and 2000 ft-1.
Most preferably, channel means (28) comprise a ceramic honeycomb, having
channels running the axial length of the recuperator reactor (27).

[0074] Referring again briefly to FIGS. 1(a) and 1(b), the inventive
reactor system includes a first reactor (7) containing a first end (9)
and a second end (11), and a second reactor (1) containing a primary end
(3) and a secondary end (5). The embodiments illustrated in FIGS. 1(a),
1(b), and 2 are merely simple illustrations provided for explanatory
purposes only and are not intended to represent a comprehensive
embodiment. Reference made to an "end" of a reactor merely refers to a
distal portion of the reactor with respect to an axial mid-point of the
reactor. Thus, to say that a gas enters or exits an "end" of the reactor,
such as end (9), means merely that the gas may enter or exit
substantially at any of the various points along an axis between the
respective end face of the reactor and a mid-point of the reactor, but
more preferably closer to the end face than to the mid-point.

[0075] With regard to the various exemplified embodiments, FIG. 3
illustrates an axial view of an exemplary gas distributor (31) having
apertures (36). Referring to both FIGS. 2 and 3, apertures (36) may
direct the second reactant gas (32) preferentially to select channels
(33). In a preferred embodiment, apertures (36) are aligned with, but are
not sealed to, the openings/apertures of select channels (33). Nozzles or
injectors (not shown) may be added to the apertures (36) that are
suitably designed to direct the flow of the second gas (32)
preferentially into the select channels (33). By not "sealing" the gas
distributor apertures (36) (or nozzles/injectors) to the select channels
(33), these channels may be utilized during the reverse flow or reaction
cycle, increasing the overall efficiency of the system. Such "open" gas
distributor (31) may be preferred for many applications, over a "closed"
system, to facilitate adaptation to multiple reactor systems, such as
where the reactor/recuperator beds may rotate or otherwise move in
relation to the location of the gas stream for processing, e.g., such as
with a rotating bed type reactor system.

[0076] When a gas distributor nozzle or aperture (36) in an "open" system
directs a stream of reactant gas (32) toward the associated inlet channel
and associated conduits in the reactor (preferably a honeycomb
monolith(s)), the contents of that stream of reactant gas (32) will
typically occupy a large number of honeycomb conduits (33) as it
traverses the recuperator. This outcome is a geometric result of the size
of the reactor segments and/or aperture size, relative to the size of the
monolith honeycomb conduits. The honeycomb conduits occupied by gas (32)
may, according to a preferred embodiment, be characterized as a bundle of
conduits, typically oriented along the same axis as the aperture (36) and
its issuing stream of gas (32). Conduits located near the center of this
bundle/channel will contain a high purity of gas (32) and thus will
likely not support exothermic reaction. Conduits located near the outer
edge of the bundle will be in close proximity to conduits (28) carrying
the other reactant. In an "open" system as described above, some mixing
of the first gas (30) and the second gas (32) will be unavoidable near
the peripheral edges of each stream of gas (32) that issues from the
apertures (36). Thus, some conduits (28) and (33) near the outer edge of
the bundle will carry some amount of both the first gas (30) and the
second gas (32). Reaction or combustion between gases (30) and (32) could
happen in these conduits before the gases completely traverse recuperator
(27). Such gases would still be considered to be substantially separated,
as long as the resulting reaction of the regeneration streams within the
recuperator (27) is less than 50 percent, preferably than less than 25
percent, and most preferably less than 10 percent of the
stoichiometrically reactive reactant having the smallest or reaction
limiting presence.

[0077] In some alternative embodiments, the recuperator reactor (27) may
include, for example, packed bed or foam monolith materials (not shown)
that permit more mixing or dispersion of reactants before fully
traversing the first reactor. In this case, additional reaction may occur
in the recuperator (27) due to mixing within the recuperator that is due
to the axial dispersion of gases (30) and (32) as they pass though. This
may still be an acceptable arrangement as long as the mixing and
subsequent reaction of the regeneration streams within the recuperator
(27) is less than 50 percent, preferably than less than 25 percent, and
most preferably less than 10 percent. Methods for calculation of radial
dispersion and mixing in bed media is known in the art.

[0078] During regeneration, the first gas (30) and second gas (32) transit
the recuperator zone (27) via channels (28) and (33). It is a key aspect
of this invention that heat, stored in the recuperator zone from the
previous quench cycle, is transferred to both the first and second gases
during the regeneration cycle. The heated gases are then introduced into
mixer (44). The gas mixer (44), located between the recuperator (27) and
the reactor (21), functions to mix the regenerating reaction gas streams
(30) and (32), preferably at or near the interface of the reaction zone
(21) and the mixer (44).

[0079] The mixer (44) is preferably constructed or fabricated of a
material able to withstand the high temperatures expected to be
experienced in the reaction zone during volatized hydrocarbon reforming
at high selectivity and high conversion rates (>50 weight percent). In
a preferred embodiment, mixer (44) is constructed from a material able to
withstand temperatures exceeding 2190° F. (1200° C.), more
preferably 2730° F. (1500° C.), and most preferably
3090° F. (1700° C.). In a preferred embodiment, mixer means
(34) is constructed of ceramic material(s) such as alumina or silicon
carbide for example.

[0080]FIG. 4 illustrates an axial view of one configuration of the mixer
(44), together with a cut-away view FIG. 4A, of one exemplary embodiment
of swirl-type mixer (47). The exemplary mixer (44) comprises mixer
segments (45) having swirl mixer (47) located within the sections (45).
In a preferred embodiment, mixer segments (45) are substantially equal in
cross sectional area and the swirl mixers (47) are generally centrally
located within the sections (45). Mixer segments (45) are positioned with
respect to the reactor system to segment the gas flow of a plurality of
gas channels (28) and (33). In a preferred embodiment, segments (45) may
each have substantially equal cross sectional area to facilitate
intercepting gas flow from a substantially equal number of gas channel
means (28) and (33). Also in a preferred embodiment, the gas channels
(28) and (33) are distributed within recuperator reactor (27) such that
each of the segments (45) intercepts gas flow from a substantially equal
fraction of both first gas channel means (28) and second gas channel
means (33). Expressed mathematically, one can define fAi as the
fraction of total cross sectional area encompassed by section i,
f28i as the fraction of total channel means (28) intercepted by
section i, and f33i as the fraction of total channel means (33)
intercepted by section i. In a preferred embodiment, for each section i,
the values f28i, and f33i will be within about 20 percent of
(i.e. between about 0.8 and 1.2 times) the value of fAi, and more
preferably within about 10 percent. One can further define f30i as
the fraction of gas stream (30) intercepted by section i, and f32i
as the fraction of gas stream (32) intercepted by the section i. In a
more preferred embodiment, for each section i, the values of f30i,
and f32i will be within about 20 percent of fAi, and more
preferably within about 10 percent.

[0081]FIG. 4A illustrates an exemplary cut out section of an individual
gas mixer segment (45) with swirl mixer (47). While the invention may
utilize a gas mixer known to the skilled artisan to combine gases from
the plurality of gas channel means (28) and (33), a preferred embodiment
of this invention minimizes open volume of the gas mixer (44) while
maintaining sufficient mixing and distribution of the mixed gases. The
term open volume means the total volume of the swirl mixers (47) and gas
mixer segment (45), less the volume of the material structure of the gas
mixer. Accordingly, gas mixer segment (45) and swirl mixer (47) are
preferably configured to minimize open volume while concurrently
providing substantial gas mixing of the gases exiting gas channels (28)
and (33). In a preferred practice of the invention, gas mixer segment
(45) dimensions L and D, are tailored to achieve sufficient mixing and
distribution of gases (31) and (32) while minimizing open volume.
Dimension ratio L/D is preferably in the range of 0.1 to 5.0, and more
preferably in the range of 0.3 to 2.5. For general segments of area A, a
characteristic diameter D can be computed as 2(A/π)1/2.

[0082] In addition, the total volume attributable to the gas mixer (44) is
preferably tailored relative to the total volume of the first reactor bed
(27) and reforming bed (21). Gas mixer (44) preferably has a total volume
of less than about 20 percent, and more preferably less than 10 percent
of the combined volume of the recuperator zone (27), the reformation zone
(21), and the gas mixer (44).

[0083] Referring again to FIG. 2, the mixer (44) as configured combines
gases from channels (33) and (28), and redistributes the combined gas
across and into reaction zone (21). In a preferred embodiment, first
reactant and second reactant are each a gas and one comprises a fuel and
the other an oxidant. Fuel may comprise hydrogen, carbon monoxide,
hydrocarbons, oxygenates, petrochemical streams, or mixtures thereof.
Oxidant typically comprises a gas containing oxygen, commonly mixed with
nitrogen, such as air. Upon mixing, the fuel and oxidant at mixer (44),
the gases combust, with a substantial proportion of the combustion
occurring proximate to the entrance to the reaction zone (21).

[0084] The combustion of the fuel and oxygen-containing gas proximate to
the entrance of the reformer or reaction zone (21) creates a hot flue gas
that heats (or re-heats) the reaction zone (21) as the flue gas travels
across that zone. The composition of the oxygen-containing gas/fuel
mixture is adjusted to provide the desired temperature of the reaction
zone. The composition and hence reaction temperature may be controlled by
adjusting the proportion of combustible to non-combustible components in
the mixture. For example, non-combustible gases or other fluids such as
H2O, CO2, and N2 also may be added to the reactant mixture
to reduce combustion temperature. In one preferred embodiment,
non-combustible gases comprise steam, flue gas, or oxygen-depleted air as
at least one component of the mixture.

[0085] Referring again to regeneration FIG. 1(b), the reacted, hot
combustion product passes through reformer (1), from the secondary end
(5) to the primary end (3), before being exhausted via conduit (18). The
flow of combustion product establishes a temperature gradient, such as
illustrated generally by example graph (8), within the reformation zone,
which gradient moves axially through the reformation reaction zone. At
the beginning of the regeneration step, this outlet temperature may
preferably have an initial value substantially equal (typically within
25° C.) to the inlet temperature of the reforming feed of the
preceding, reforming, step. As the regeneration step proceeds, this
outlet temperature will increase somewhat as the temperature profile
moves toward the outlet, and may end up 50° C. to 200° C.
above the initial outlet temperature. Preferably, the heated reaction
product in the regeneration step heats at least a portion of the second
reactor, preferably the secondary end (5) of the second reactor (1), to a
temperature of at least about 1500° C., and more preferably to a
temperature of at least about 1600° C., and still more preferably
in some processes to a temperature of at least about 1700° C.
Temperature and residency time are both relevant to controlling the
reaction speed and product.

[0086] Reactor system cycle time includes the time spent at regeneration
plus the time spent at reforming, plus the time required to switch
between regeneration and reformation and vice versa. Thus, a half cycle
may be the substantially the time spent only on regeneration, or the time
spend on reformation. A complete cycle includes heating the bed, feeding
the volatized hydrocarbon, and quenching the acetylene containing
reaction product. Typical cycle times for preferred embodiments utilizing
honeycomb monoliths may be between 1 second and 240 seconds, although
longer times may be desired in some alternative embodiments. More
preferably for the preferred monolith embodiments, cycle times may be
between 2 seconds and 60 seconds. It is not necessary that the
regeneration and reformation steps to have equal times, and in a
well-refined application it is likely that these two times will not be
equal.

[0087] As discussed above, in one preferred aspect, provided is a process
for pyrolyzing a hydrocarbon feedstock containing nonvolatiles in a
regenerative pyrolysis reactor system, said process comprising: (a)
heating the nonvolatile-containing hydrocarbon feedstock upstream of a
regenerative pyrolysis reactor system to a temperature sufficient to form
a vapor phase that is essentially free of nonvolatiles and a liquid phase
containing the nonvolatiles; (b) separating said vapor phase from said
liquid phase; (c) feeding the separated vapor phase to the pyrolysis
reactor system; and (d) converting the separated vapor phase in said
pyrolysis reactor system to form a pyrolysis product.

[0088] In another aspect, the invention includes a process for the
manufacture of a hydrocarbon pyrolysis product from a hydrocarbon feed
using a regenerative pyrolysis reactor system, wherein the reactor system
includes (i) a first reactor comprising a first end and a second end, and
(ii) a second reactor comprising primary end and a secondary end, and the
first and second reactors are oriented in a series flow relationship with
respect to each other such that the secondary end of the second reactor
is proximate the second end of the first reactor, the process comprises
the steps of: (a) heating a nonvolatile-containing hydrocarbon feedstock
upstream of the regenerative pyrolysis reactor system to a temperature
sufficient to form a vapor phase that is essentially free of nonvolatiles
and a liquid phase containing the nonvolatiles; (b) separating the vapor
phase from the liquid phase; (c) supplying a first reactant through a
first channel in the first reactor and supplying at least a second
reactant through a second channel in the first reactor, such that the
first and second reactants are supplied to the first reactor from the
first end of the first reactor; (d) combining the first and second
reactants at the second end of the first reactor and reacting the
combined reactants to produce a heated reaction product; (e) passing the
heated reaction product through the second reactor to transfer heat from
the reaction product to the second reactor to produce a heated second
reactor; (f) transferring at least a portion of the separated vapor phase
from step (b), and including any co-feed such as hydrogen, hydrogen
donor, diluent, stripping agent, methane, etc., to the pyrolysis reactor
system, and through the heated second reactor to convert at least a
portion of the vapor feed into a pyrolysis product; (g) quenching the
pyrolysis product, preferably in the first reactor, to halt the
conversion reaction; and (h) recovering the quenched pyrolysis product
from the reactor system.

[0089] The present invention also includes an apparatus for pyrolyzing a
hydrocarbon feedstock containing nonvolatiles in a regenerative pyrolysis
reactor system, said apparatus comprising: (a) a heater to heat a
nonvolatile-containing hydrocarbon feedstock to a temperature sufficient
to form a vapor phase that is essentially free of nonvolatiles and a
liquid phase containing the nonvolatiles; (b) a separator to separate the
vapor phase from the liquid phase; and (c) a regenerative pyrolysis
reactor system to receive the separated vapor phase, heat and convert the
separated vapor phase in the pyrolysis reactor system to form a pyrolysis
product.

[0090] In yet another embodiment, the present invention includes an
apparatus for the manufacture of a hydrocarbon pyrolysis product from a
hydrocarbon feed using a regenerative pyrolysis reactor system, the
apparatus comprising: (a) a heater to heat a nonvolatile-containing
hydrocarbon feedstock to a temperature sufficient to form a vapor phase
that is essentially free of nonvolatiles and a liquid phase containing
the nonvolatiles; (b) a separator to separate the vapor phase from the
liquid phase; and (c) a regenerative pyrolysis reactor system to receive
the separated vapor phase and convert the separated vapor phase in said
pyrolysis reactor system to form a pyrolysis product, the regenerative
pyrolysis reactor system including; (i) a first reactor comprising a
first end and a second end; and (ii) a second reactor comprising primary
end and a secondary end, the first and second reactors are oriented in a
series flow relationship with respect to each other; wherein the first
reactor comprises a first channel for conveying a first reactant through
the first reactor and a second channel for conveying a second reactant
through the reactor.

[0091] While the present invention has been described and illustrated with
respect to certain embodiments, it is to be understood that the invention
is not limited to the particulars disclosed and extends to all
equivalents within the scope of the claims.